Answered step by step
Verified Expert Solution
Link Copied!

Question

1 Approved Answer

This assignment has you writing an encrypting / decrypting utility for Linux. This utility will take any ASCII file and encrypt it in such a

This assignment has you writing an encrypting / decrypting utility for Linux. This utility will take any ASCII file and encrypt it in such a way that its contents are not readable until they are decrypted by the utility. Objectives Practice creating a software project in Linux in the required development directory structure Practice creating a makefile for a Linux software project Reinforce C Programming techniques - File I/O using ASCII files, Command-Line Processing Requirements 1. The utility needs to be called cryptoMagic and needs to be written in C a. The utility has 2 command-line switches they are encrypt and decrypt b. If none of these switches is specified, then encrypt is assumed c. The utility also takes the name of an ASCII input file to encrypt/decrypt as an argument d. For example: cryptoMagic encrypt myFile.txt will encrypt the contents of the myFile.txt file cryptoMagic myFile.txt will encrypt the contents of the myFile.txt file cryptoMagic decrypt myFile.crp will decrypt the contents of the myFile.crp file 2. When the utility is asked to encrypt an ASCII file, it will take the input filename and produce the encrypted file with the same base filename and an .crp file extension a. For example: cryptoMagic encrypt myFile.txt will produce an encrypted file called myFile.crp 3. When the utility is asked to decrypt an encrypted file, it will take the input filename and produce the decrypted file with the same base filename and an .txt File extension a. For example: cryptoMagic decrypt myFile.crp will produce a decrypted file called myFile.txt 4. It should be noted that the input file can have any file extension. When asked to encrypt, you need to replace the existing file extension (if any) with .TXT. Similarly when asked to decrypt, you need to replace the existing file extension (if any) with .CRP 5. Each line (up to and including the carriage return (noted as below)) in the unencrypted ASCII file is guaranteed of being less than 120 characters. While processing the input ASCII file you need to process one line at a time. Continue to process the input file until you reach the end of the file. a. Please note that it is not guaranteed that each line actually ends in a carriage return ... how will you handle that? 6. The encryption scheme is applied to each character in the line: a. If the character is a (ASCII value 9) then simply transform it into the output character sequence TT b. The carriage return characters are not to be encrypted they are left as is in the resultant output file (the in the example below is meant for illustration only do not output ) c. If is not a tab or a carriage return character, then apply the encryption scheme in steps d through f below d. Take the ASCII code for the input character and subtract a value of 16 from it. Lets call this resultant value outChar e. If the resulting outChar value is less than 32, then another step must be taken: outChar = (outChar 32)+ 144 f. You need to write the ASCII value of the new encrypted character (i.e. outChar) to the destination file as a 2 digit hexadecimal value. Note that this will effectively double the length of the input line in terms of size ... For example if the input (unencrypted) file is: Hello There how are you? My name is Sean Clarke. I like software! Then the encrypted file is: 38555C5C5F80445855625580585F678051625580695F652F 3D69805E515D55805963804355515E80335C51625B558ETT39805C595B5580635F56646751625581 7. Each line (up to an including the carriage return (if it exists)) in the encrypted ASCII file is guaranteed of being less than 255 characters. Remember - while processing the input ASCII file you need to process one line at a time. 8. The decryption scheme is applied to each pair of characters in the input line: a. You need to see if the pair of characters you are processing is the sequence TT if so, then simply transform this pair of characters into a character (ASCII value 9) in the output file. b. If the pair of characters is not the sequence TT, then translate the first character of the pair by multiplying its face value by 16. Remember that hex values of A through F take on the face values of 10 through 15. Then add the face value of the second character in the pair. Lets call the resulting value outChar. For example: i. Reading the pair of characters 38 from the encrypted file will translate into an outChar value of 56 decimal. ii. Reading the pair of characters 5C from the encrypted file will translate into an outChar value of 92 decimal. c.Now you need to add 16 to outChar. d. If the resulting outChar value is greater than 127, then another step must be taken: outChar = (outChar - 144) + 32 e. The outChar value now contains the decrypted ASCII code for the character that you have just decoded. So take this decrypted character value (i.e. outChar) and write it to the destination file as a character. f. The carriage return characters are not to be decrypted they are left as is in the resultant file. For example if the input (encrypted) file is: 4458596380555E5362696064595F5E80635358555D55805963806062556464698067555962548E 39635E87648059642F812F Then the decrypted file is: This encryption scheme is pretty weird. Isn't it?!? 9.It is expected that your cryptoMagic utility has been tested (perhaps by using the above examples) as well as with any other encrypted / decrypted examples you can think of. Dont forget about the extreme / boundary test cases! 10. It is expected that your cryptoMagic utility has been designed using modular techniques (i.e. the program has been written using functions that youve created). a. The solution must have at least 2 source files and 1 include file b. There should be no debugging messages present in your final submitted utility 11. Your solution structure must include a makefile and also follow the recommended Linux development directory structure as outlined in the Linux-Development-Project-Code-Structure document

Step by Step Solution

There are 3 Steps involved in it

Step: 1

blur-text-image

Get Instant Access to Expert-Tailored Solutions

See step-by-step solutions with expert insights and AI powered tools for academic success

Step: 2

blur-text-image_2

Step: 3

blur-text-image_3

Ace Your Homework with AI

Get the answers you need in no time with our AI-driven, step-by-step assistance

Get Started

Recommended Textbook for

Machine Learning And Knowledge Discovery In Databases European Conference Ecml Pkdd 2015 Porto Portugal September 7 11 2015 Proceedings Part 1 Lnai 9284

Authors: Annalisa Appice ,Pedro Pereira Rodrigues ,Vitor Santos Costa ,Carlos Soares ,Joao Gama ,Alipio Jorge

1st Edition

3319235273, 978-3319235271

More Books

Students also viewed these Databases questions

Question

Can workers be trained in ethics? How? Defend your answer.

Answered: 1 week ago